The invention is concerned with a so-called shaker device for use in automobile and the like alarm systems.
The shaker of an automobile alarm system is a device which has a vibratory member that is supported for free movement at one end thereof, the freely moving end being provided with an electrical contact. There is another member having a cooperating contact disposed in a position to be engaged by the moving contact when the amplitude of the vibratory member is great enough.
The vibratory member is usually a substantially flat steel spring supported at one end and having a heavy weight at the other end to decrease the period of vibration and to provide a relatively greater amplitude of vibration than such a spring without a weight. If contact is made an alarm is energized. If the vehicle is standing a sharp blow or movement of the vehicle will set the vibratory member moving and sound the alarm.
The known construction of shaker has several disadvantages. One is that the normal movement of the automobile or other vehicle produces a continuous vibration even when the alarm system is turned off and this in turn knocks repeatedly on the housing of the shaker. This is annoying to the occupants of the vehicle. A second disadvantage is that the movement of the car occupant getting out of the vehicle sets the vibratory member of the known construction vibrating for a relatively long time requiring the occupant to wait until the amplitude has decreased to an extent that the vibratory member does not make electrical contact with the fixed contact so that the alarm can be armed without being immediately sounded.
In order to decrease the time of vibration and dampen the movement of the vibratory member it has been known to secure a damping member on the vibratory member and bumpers on the interior of the shaker housing to deaden the sound of the weight striking the housing. The cost of the damping member and the bumpers and the labor in installing the same increase the cost of the shaker device while not contributing functionally to the operation of the device in the alarm system.
The invention eliminates the bumpers and provides a novel damping device which decreases the amplitude and period of vibration of the vibratory member.